CN110582527A

CN110582527A - Thermoplastic composite material

Info

Publication number: CN110582527A
Application number: CN201880027118.XA
Authority: CN
Inventors: H·阿梅德罗; J-M·科帕特; N·雅克; R·塞恩特-鲁普
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-05-05
Filing date: 2018-05-07
Publication date: 2019-12-17
Anticipated expiration: 2038-05-07
Also published as: PT3619255T; US20200190317A1; MX2019013112A; CA3062456A1; JP7195272B2; FR3065957B1; JP2020518690A; EP3619255A1; KR102548681B1; US11130860B2; FR3065957A1; KR20190141671A; CN110582527B; EP3619255B1; WO2018202917A1; ES2874792T3

Abstract

The invention relates to a thermoplastic composite material based on: a thermoplastic polymer matrix comprising an amorphous polyester comprising 1,4:3, 6-dianhydrohexitol units, a cycloaliphatic diol, and terephthalic acid; and thermoplastic fibers comprising a semi-crystalline polyester containing 1,4:3, 6-dianhydrohexitol units, a cycloaliphatic diol, and terephthalic acid. The invention also relates to a method for producing said composite material.

Description

thermoplastic composite material

Technical Field

The present invention relates to the field of materials and to a thermoplastic composite material and a method for its manufacture, said composite material being particularly suitable for recycling.

Technical Field

Plastic materials, and in particular thermoplastic polymers, are widely used in industry to manufacture many products due to their mechanical properties. Accordingly, manufacturers are constantly searching for novel methods that allow for improvements in the properties of existing polymers, or for novel polymers with improved properties.

For this reason, in order to increase the mechanical strength of the polymer, it is known to incorporate various compounds therein in order to obtain composite materials with improved mechanical properties. These various compounds act as reinforcements, significantly improving the mechanical behavior of the polymers into which they are incorporated. These reinforcements are usually fibers, such as natural fibers, synthetic fibers, carbon fibers or even glass fibers.

In recent years, the composite market has shown a continuous growth. Therefore, many active areas, such as medicine, sports, automobiles, or green energy sources, are integrating these materials into their product design.

composite materials constitute a new source of innovation and offer new growth opportunities for the industry. They are defined as materials consisting of reinforcements and matrix and are distinguished from other synthetic plastic products by the following features: making them invariant and low weight properties possible in some cases to replace metal parts.

However, as with any material, recycling problems inevitably arise when the material is produced on a large scale.

The inhomogeneities associated with the composite material nature give the composite material major benefits through the combined properties of the matrix and the fibres, but this is also a parameter that makes them difficult to recycle. Furthermore, composite materials are anisotropic, that is to say the properties are not the same in all directions, and they may contain foams, inserts or in some cases even sensors. Therefore, there are so many materials to be disposed of that their recycling is complicated and expensive.

for several years, efforts have focused on composite materials consisting of a thermoset matrix. Indeed, these "thermoset" composites comprise greater than 95% of the composites used in the industry. Alternatively, "thermoplastic" composites have been developed and have the following advantages that are not insignificant: having a matrix that can be melted and reshaped, an advantage that is not possible with thermoset materials, thereby promoting the possibility of recycling.

Nevertheless, when the problem is to separate the fibers from the matrix in order to recycle these materials, the problem remains the same for both families of composite materials. The most complex technique in which the matrix is broken down without degrading the fibers is still in the experimental stage for the most part. These are for example the following techniques for recycling reusable fibres: such as solvolysis, pyrolysis or thermolysis involving chemistry, heat or thermodynamics.

Currently, there are a number of technical options for recycling composite materials. Thus, recycling can be achieved by chemical, thermal (other than incineration), mechanical, by incineration, or as a last resort by disposal.

Mechanical techniques may include grinding the composite part at the end of its useful life and thus enable the material to be recycled in powder form. In some cases, this material is returned to the field of plastics processing in order to use it for making process parts, but generally these powders are used to produce concrete volumes at low cost, for example in competition with sand or talc in particular.

Incineration has also proven to be a well-developed alternative. In this particular case, the problem is not recycling itself, but creating value, since by burning the ground composite it is thus possible to recover thermal energy from the matrix (itself derived from the oil). Cement plants with furnaces that can be heated to 2000 c are ideal customers.

however, the fact remains that in order to create value from 90% of the composite waste currently sent to landfills, there is a need to find alternatives and develop novel composite materials that can be easily recycled.

it is therefore worth mentioning that the applicant, after significant research, has developed a completely thermoplastic composite material with an hitherto never achieved ease of recycling, which can be completely recycled without having to separate the fibres from the matrix.

Disclosure of Invention

Accordingly, a first subject of the present invention relates to a thermoplastic composite comprising:

-a thermoplastic polymer matrix comprising an amorphous thermoplastic polyester comprising at least one 1,4:3, 6-dianhydrohexitol unit (A), at least one cycloaliphatic diol unit (B) other than the 1,4:3, 6-dianhydrohexitol units (A), at least one terephthalic acid unit (C), wherein the ratio of (A)/[ (A) + (B) ] is at least 0.32 and at most 0.75, said polyester being free of any aliphatic acyclic diol unit or comprising an aliphatic acyclic diol unit in a molar amount of less than 5% relative to all monomer units of the polyester, and the solution reduced viscosity of said polyester (25 ℃; phenol (50% m): o-dichlorobenzene (50% m); 5g/l of polyester) being greater than 50ml/g,

-thermoplastic polymer fibres, said fibres comprising a semi-crystalline thermoplastic polyester comprising at least one 1,4:3, 6-dianhydrohexitol unit (a), at least one cycloaliphatic diol unit (B) other than the 1,4:3, 6-dianhydrohexitol units (a), at least one terephthalic acid unit (C), wherein the ratio of (a)/[ (a) + (B) ] is at least 0.05 and at most 0.30, said polyester being free of any aliphatic acyclic diol unit or comprising an aliphatic acyclic diol unit in a molar amount of less than 5% relative to all monomer units of the polyester, and the solution reduced viscosity (25 ℃; phenol (50% m): o-dichlorobenzene (50% m); 5g/l of polyester) of said polyester is greater than 50 ml/g.

A second subject matter relates to a method for producing a thermoplastic composite material, comprising the steps of:

a) A polymer matrix as described previously is provided,

b) A polymer fiber as described previously is provided,

c) Preparing a thermoplastic composite from the matrix and the fibers.

The thermoplastic composite material according to the invention is completely thermoplastic (both matrix and fibre reinforcement) and has in particular the following advantages: the recycling and utilization easiness which has not been realized so far is obtained.

Indeed, the completely thermoplastic character of the composite material according to the invention makes it possible in particular to dispense with the separation steps that are usually carried out. Thus, recycling is more efficient, less expensive, and enables uniform thermoplastic materials to be obtained that can be used in a variety of plastic applications, rather than composites. The thermoplastic composite material according to the invention is therefore a technical breakthrough in terms of recycling and creating value from materials, and in particular thermoplastic materials.

Detailed Description

-a thermoplastic polymer matrix comprising an amorphous thermoplastic polyester comprising at least one 1,4:3, 6-dianhydrohexitol unit (A), at least one cycloaliphatic diol unit (B) other than the 1,4:3, 6-dianhydrohexitol units (A), at least one terephthalic acid unit (C), wherein the molar ratio of (A)/[ (A) + (B) ] is at least 0.32 and at most 0.75, said polyester being free of any aliphatic acyclic diol unit or comprising an aliphatic acyclic diol unit in a molar amount of less than 5% relative to all the monomer units of the polyester, and the solution reduced viscosity of said polyester (25 ℃; phenol (50% m): o-dichlorobenzene (50% m); 5g/l of polyester) is greater than 50ml/g,

-thermoplastic polymer fibres, said fibres comprising a semi-crystalline thermoplastic polyester comprising at least one 1,4:3, 6-dianhydrohexitol unit (A), at least one cycloaliphatic diol unit (B) other than the 1,4:3, 6-dianhydrohexitol units (A), at least one terephthalic acid unit (C), wherein the molar ratio of (A)/[ (A) + (B) ] is at least 0.05 and at most 0.30, the polyester is free of any aliphatic acyclic diol units or contains an aliphatic acyclic diol unit in a molar amount of less than 5% relative to all monomer units of the polyester, and the solution reduced viscosity (25 ℃; phenol (50% m): o-dichlorobenzene (50% m); 5g/l of polyester) of the polyester is greater than 50 ml/g.

Thus, the thermoplastic composite according to the invention comprises a thermoplastic matrix comprising an amorphous thermoplastic polyester.

More particularly, it is a thermoplastic polyester comprising: at least one 1,4:3, 6-dianhydrohexitol unit (A), at least one cycloaliphatic diol unit (B) other than the 1,4:3, 6-dianhydrohexitol units (A), at least one terephthalic acid unit (C), wherein the molar ratio of (A)/[ (A) + (B) ] is at least 0.32 and at most 0.75.

the thermoplastic polyester does not contain any aliphatic acyclic diol units, or contains a small molar amount of aliphatic acyclic diol units.

"minor molar amount of aliphatic acyclic diol units" is intended to mean in particular a molar amount of aliphatic acyclic diol units of less than 5%. According to the invention, this molar amount represents the ratio of the sum of the aliphatic acyclic diol units (which may be identical or different) relative to all the monomer units of the polyester.

Advantageously, the molar amount of aliphatic acyclic diol units is less than 1%. Preferably, the polyester does not contain any aliphatic acyclic diol units, and more preferably it does not contain any ethylene glycol.

The aliphatic acyclic diol may be a linear or branched aliphatic acyclic diol. It may also be a saturated or unsaturated aliphatic acyclic diol. The saturated linear aliphatic acyclic diol may be, for example, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 8-octanediol and/or 1, 10-decanediol, in addition to ethylene glycol. As examples of saturated branched aliphatic acyclic diols, mention may be made of 2-methyl-1, 3-propanediol, 2, 4-trimethyl-1, 3-pentanediol, 2-ethyl-2-butyl-1, 3-propanediol, propylene glycol and/or neopentyl glycol. As examples of unsaturated aliphatic diols, mention may be made of, for example, cis-2-butene-1, 4-diol.

Despite the low amount of aliphatic acyclic diols used for the synthesis and thus of ethylene glycol, thermoplastic polyesters are obtained which have a high solution reduced viscosity and in which isosorbide is incorporated particularly well.

Monomer (A) is a1, 4:3, 6-dianhydrohexitol and may be isosorbide, isomannide, isoidide, or a mixture thereof. Preferably, the 1,4:3, 6-dianhydrohexitol (A) is isosorbide.

Isosorbide, isomannide and isoidide can be obtained by dehydration of sorbitol, mannitol and iditol, respectively. As regards isosorbide, it is known by the applicant under the trade name isosorbideAnd P is sold.

The alicyclic diol (B) is also called an aliphatic and cyclic diol. It is a diol which may be chosen, in particular, from 1, 4-cyclohexanedimethanol, 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol or mixtures of these diols. The cycloaliphatic diol (B) is very preferably 1, 4-cyclohexanedimethanol. The cycloaliphatic diol (B) may be in the cis configuration, in the trans configuration, or may be a mixture of diols in the cis and trans configurations.

The molar ratio of the sum of the 1,4:3, 6-dianhydrohexitol units (A)/1,4:3, 6-dianhydrohexitol units (A) and the cycloaliphatic diol units (B) other than these 1,4:3, 6-dianhydrohexitol units (A) (i.e., (A)/[ (A) + (B) ]) is at least 0.32 and at most 0.75. In this way, the thermoplastic polyester is amorphous and is characterized by the absence of X-ray diffraction lines and the absence of endothermic melting peaks in Differential Scanning Calorimetry (DSC) analysis.

Amorphous thermoplastic polyesters particularly suitable for thermoplastic composites include:

1,4:3, 6-dianhydrohexitol units (A) in a molar amount ranging from 16% to 54%;

Alicyclic diol units (B) other than these 1,4:3, 6-dianhydrohexitol units (A) in a molar amount ranging from 5% to 30%;

terephthalic acid units (C) in a molar amount ranging from 45% to 55%.

The amount of the different units in the polyester may be determined by¹H NMR or by chromatographic analysis of the monomer mixture resulting from complete hydrolysis or methanolysis of the polyester; these amounts are preferably determined by¹H NMR determination.

The person skilled in the art can easily find the analytical conditions for determining the amount of units of the polyester. For example, from the NMR spectrum of poly (1, 4-cyclohexanedimethylene-co-isosorbide terephthalate), the chemical shifts for 1, 4-cyclohexanedimethanol are between 0.9ppm and 2.4ppm and 4.0ppm and 4.5ppm, the chemical shifts for the terephthalate ring are between 7.8ppm and 8.4ppm, and the chemical shifts for isosorbide are between 4.1ppm and 5.8 ppm. The integration of each signal allows the amount of each unit of polyester to be determined.

The amorphous thermoplastic polyesters used according to the invention have a glass transition temperature ranging from 116 ℃ to 200 ℃, for example from 140 ℃ to 190 ℃.

the glass transition temperature is measured by conventional methods and in particular by Differential Scanning Calorimetry (DSC) methods using a heating rate of 10 ℃/min. The experimental protocol is described in detail in the examples section below.

The amorphous thermoplastic polyester has in particular a lightness L of more than 40. Lightness should be understood in the sense of a Hunter (Hunter) color value, where lightness is the brightness of a surface derived from an object. Advantageously, the lightness L is greater than 55, preferably greater than 60, most preferably greater than 65, for example greater than 70. The parameter L may be determined via the CIE Lab model using a spectrophotometer.

Finally, the solution has a reduced viscosity of more than 50ml/g and less than 120ml/g, which enables the polymer to be dissolved at 130 ℃ with stirring and then introduced at a concentration of 5g/l, measured at 25 ℃ in an equal mass mixture of phenol and o-dichlorobenzene, using an Ubbelohde capillary viscometer.

the amorphous character of the thermoplastic polyesters used according to the invention is characterized by the absence of X-ray diffraction lines and also by the absence of endothermic melting peaks in Differential Scanning Calorimetry (DSC) analysis.

According to a particular embodiment, the thermoplastic composite according to the invention comprises from 20% to 70% by weight, preferentially from 30% to 60% by weight, of the amorphous thermoplastic polyester matrix as previously described.

According to one embodiment, the thermoplastic matrix of the composite material according to the invention consists essentially of amorphous thermoplastic polyester.

The thermoplastic composite according to the invention also comprises thermoplastic fibers comprising a semicrystalline thermoplastic polyester.

The term "fiber" as used in the present invention is synonymous with the terms filament and yarn and thus includes continuous or discontinuous monofilament or multifilament, non-twisted or intermingled multifilament, raw yarn. In addition, the term "fiber" is also used regardless of the form in which the fiber is found (i.e., in woven or non-woven form).

The semicrystalline thermoplastic polyester fibers serve as reinforcement in the thermoplastic composite according to the invention.

More particularly, the semi-crystalline thermoplastic polyester used to obtain the fibres is a thermoplastic polyester comprising: at least one 1,4:3, 6-dianhydrohexitol unit (A), at least one cycloaliphatic diol unit (B) other than the 1,4:3, 6-dianhydrohexitol units (A), at least one terephthalic acid unit (C), wherein the ratio of (A)/[ (A) + (B) ] is at least 0.05 and at most 0.30, said polyester being free of any aliphatic acyclic diol unit or comprising an aliphatic acyclic diol unit in a molar amount of less than 5% relative to all monomer units of the polyester, and the solution reduced viscosity of said polyester (25 ℃; phenol (50% m): o-dichlorobenzene (50% m); 5g/l of polyester) is greater than 50 ml/g.

the monomer (A) and the alicyclic diol (B) are as described above for the amorphous thermoplastic polyester.

The molar ratio of the sum of the 1,4:3, 6-dianhydrohexitol units (A)/1,4:3, 6-dianhydrohexitol units (A) and the cycloaliphatic diol units (B) other than these 1,4:3, 6-dianhydrohexitol units (A) (i.e., (A)/[ (A) + (B) ]) is at least 0.05 and at most 0.30. Advantageously, this ratio is at least 0.1 and at most 0.28, and more particularly this ratio is at least 0.15 and at most 0.30.

The semi-crystalline thermoplastic polyesters particularly suitable for obtaining the fibers according to the invention comprise:

1,4:3, 6-dianhydrohexitol units (A) in a molar amount ranging from 2.5 mol% to 15 mol%;

Alicyclic diol units (B) other than these 1,4:3, 6-dianhydrohexitol units (A) in a molar amount ranging from 30 to 42.5 mol%;

A molar amount of terephthalic acid units (C) ranging from 45 to 55 mol%.

The fibers obtained with the semi-crystalline thermoplastic polyesters described above advantageously have a melting point ranging from 210 ℃ to 295 ℃, for example from 240 ℃ to 285 ℃.

Furthermore, the semi-crystalline thermoplastic polyester has a glass transition temperature ranging from 85 ℃ to 120 ℃, for example from 90 ℃ to 115 ℃.

The glass transition temperature and melting point are measured by conventional methods, in particular using Differential Scanning Calorimetry (DSC), with a heating rate of 10 ℃/min. The experimental protocol is also described in detail in the examples section below.

Advantageously, the semi-crystalline thermoplastic polyester has a heat of fusion of greater than 10J/g, preferably greater than 20J/g, the measurement of this heat of fusion comprising subjecting a sample of this polyester to a heat treatment at 170 ℃ for 16 hours, then evaluating this heat of fusion by DSC by heating the sample at 10 ℃/min.

The semi-crystalline thermoplastic polyester used according to the invention has in particular a lightness L of greater than 40. Advantageously, the lightness L is greater than 55, preferably greater than 60, most preferably greater than 65, for example greater than 70. The parameter L may be determined via the CIELab model using a spectrophotometer.

Finally, the solution reduced viscosity of the semi-crystalline thermoplastic polyester is greater than 50ml/g and preferably less than 120ml/g, this viscosity being such as to enable, after dissolution of the polymer at 130 ℃ with stirring, a concentration of 5g/l of polymer introduced at 25 ℃ in an equal mass mixture of phenol and o-dichlorobenzene, measured using an Ubbelohde capillary viscometer.

As previously developed for thermoplastic matrices, this test for measuring the reduced viscosity of solutions is perfectly suitable for determining the viscosity of semi-crystalline thermoplastic polymers, due to the choice of solvent and the concentration of the polymer used.

The semi-crystalline nature of the thermoplastic polyesters used according to the invention is distinguished when the latter have X-ray diffraction lines or absorption thermal melting peaks in Differential Scanning Calorimetry (DSC) analysis after heat treatment for 16h at 170 ℃.

Starting from semi-crystalline thermoplastic polyesters as defined previously, the fibers according to the invention can be obtained according to methods known to those skilled in the art, such as melt-spinning methods or by processes in solution (also known as wet or dry processes). Preferably, the fibers are obtained by a melt-spinning process.

the fibers may be woven fibers, non-woven fibers, or a blend of woven and non-woven fibers. The nonwoven may consist of a web, cloth, lap, or a mat of oriented or randomly distributed fibers, the cohesion of which is provided by mechanical, physical or chemical means, or by a combination of these means. An example of an internal cohesion may be the adhesion and the resulting nonwoven, which may then be made in the form of a felt of fibers.

According to a particular embodiment, the fibers of the thermoplastic composite are woven fibers. The weaving of the fibres may be performed according to plain (taffeta), twill, satin or even unidirectional interlacing, and preferably according to plain interlacing.

According to another embodiment, the fibers of the thermoplastic composite are non-woven. The nonwoven fibers may be obtained according to techniques known to those skilled in the art, such as dry route, melt route, wet route or flash spinning. For example, the formation of nonwoven fibers by dry-laid lines can be carried out in particular by calendering or by air-laying. As regards production by the melt route, it can be carried out by extrusion (spunbond technique or spunbond fabric) or by extrusion blow-moulding (meltblown).

The polyester fibers according to the invention have very good properties from both a mechanical and a thermal point of view and constitute a reinforcement which is particularly suitable for the selection of thermoplastic composites. Indeed, the fibers according to the invention have an improvement, for example in mechanical properties (such as elongation at break or durability) compared to conventional polymer fibers.

Furthermore, the use of the fibers according to the invention for the manufacture of thermoplastic composites is particularly advantageous in that it also makes it possible to avoid putrefaction phenomena that may sometimes occur in certain natural fibers.

According to one embodiment, the thermoplastic composite comprises from 30 to 80% by weight, preferentially from 40 to 70% by weight of the semi-crystalline thermoplastic polyester fibers as previously described.

according to one embodiment, the thermoplastic fibers of the composite material according to the invention consist essentially of a semi-crystalline thermoplastic polyester.

According to one embodiment, the thermoplastic composite material consists essentially of a thermoplastic matrix as defined previously and thermoplastic fibers as defined previously.

The thermoplastic composite material according to the invention is particularly advantageous. Unlike current composites, the thermoplastic composite according to the invention is completely thermoplastic (both matrix and fiber reinforcement), with the direct result that an easy recycling is obtained which has never been achieved to date. Thus, the inventors have found in a completely original way that the chemical similarity of the matrix and the fibers according to the invention enables to obtain a transesterification reaction between said matrix and said fibers during heating to a temperature greater than the melting point (Mp) of the fibers, thereby producing a thermoplastic material comprising compatible phases or even completely homogeneous (depending on the recycling conditions used).

to date, even though the matrices of thermoplastic composites can melt, they still have the same difficulties with respect to fiber/matrix separation as with thermomuctile composites for recycling. Now, since the composite material according to the invention is completely thermoplastic, the conventionally performed separation step is eliminated. Thus, recycling is more efficient, less expensive, and enables uniform thermoplastic materials to be obtained that can be used in a variety of plastic applications, rather than composites. The thermoplastic composite material according to the invention is therefore a technical breakthrough in terms of recycling and creating value from materials, and in particular thermoplastic materials. It is understood that the composite material according to the invention has at least the same mechanical properties as thermoplastic composite materials consisting of reinforcements that have been conventionally used hitherto.

Amorphous thermoplastic polyesters particularly suitable for obtaining thermoplastic matrices can be prepared by a synthesis process comprising:

a step of introducing into a reactor monomers comprising at least one 1,4:3, 6-dianhydrohexitol (A), at least one cycloaliphatic diol (B) other than the 1,4:3, 6-dianhydrohexitol (A), and at least one terephthalic acid (C), the molar ratio of (A)/[ (A) + (B) ] being at least 0.32 and at most 0.75, and the ratio of ((A) + (B))/(C) being in the range from 1.05 to 1.5, said monomers being free of any aliphatic acyclic diol or comprising aliphatic acyclic diol units in a molar amount of less than 5% relative to all monomers introduced;

A step of introducing a catalytic system into the reactor;

a step of polymerizing the monomers to form a polyester, the step consisting of:

■ a first stage of oligomerization during which the reaction medium is stirred under an inert atmosphere at a temperature ranging from 265 ℃ to 280 ℃, advantageously from 270 ℃ to 280 ℃, for example 275 ℃;

■, during which the oligomer formed is stirred under vacuum at a temperature ranging from 278 ℃ to 300 ℃, advantageously from 280 ℃ to 290 ℃, for example 285 ℃ in order to form a polyester;

A step of recovering the thermoplastic polyester.

This first stage of the process is carried out under an inert atmosphere, i.e. under an atmosphere of at least one inert gas. The inert gas may in particular be dinitrogen. This first stage may be carried out under a gas flow and it may also be carried out under pressure, for example at a pressure between 1.05 and 8 bar.

Preferably, the pressure ranges from 3 to 8 bar, most preferably from 5 to 7.5 bar, e.g. 6.6 bar. Under these preferred pressure conditions, the reaction of all the monomers with each other is promoted by limiting the loss of monomers during this phase.

Prior to the first stage of oligomerization, a deoxygenation step of the monomers is preferably carried out. For example, once the monomer is introduced into the reactor, it may be carried out by creating a vacuum and then by introducing an inert gas such as nitrogen thereto. This cycle of vacuum-inert gas introduction may be repeated several times, for example from 3 to 5 times. Preferably, this vacuum-nitrogen cycle is carried out at a temperature between 60 ℃ and 80 ℃ so that the reagents and in particular the diol are completely molten. This deoxygenation step has the advantage of improving the colouring characteristics of the polyester obtained at the end of the process.

The second stage of condensation of the oligomer is carried out under vacuum. During this second phase, the pressure may be continuously reduced by using a pressure reduction gradient, stepwise, or using a combination of pressure reduction gradients and steps. Preferably, at the end of this second stage, the pressure is less than 10 mbar, most preferably less than 1 mbar.

The first stage of the polymerization step preferably has a duration ranging from 20 minutes to 5 hours. Advantageously, the second phase has a duration ranging from 30 minutes to 6 hours, the start of which is the moment when the reactor is placed under vacuum, that is to say at a pressure of less than 1 bar.

The method further comprises the step of introducing a catalytic system into the reactor. This step may be carried out beforehand or during the above-mentioned polymerization step.

Catalytic system is intended to mean a catalyst or a mixture of catalysts, optionally dispersed or immobilized on an inert support.

The amount of catalyst is suitable to obtain a high viscosity polymer to obtain a polymer composition.

An esterification catalyst is advantageously used during the oligomerization stage. The esterification catalyst may be selected from tin derivatives, titanium derivatives, zirconium derivatives, hafnium derivatives, zinc derivatives, manganese derivatives, calcium derivatives and strontium derivatives, organic catalysts such as p-toluene sulfonic acid (PTSA) or Methane Sulfonic Acid (MSA), or mixtures of these catalysts. By way of examples of such compounds, mention may be made of those given in application US 2011282020 a1 in paragraphs [0026] to [0029] and in application WO 2013/062408 a1 on page 5.

Preferably, during the first stage of the transesterification, a zinc derivative or a manganese, tin or germanium derivative is used.

by way of example of amounts by weight, from 10 to 500ppm of the metal contained in the catalytic system can be used during the oligomerization stage, with respect to the amount of monomer introduced.

At the end of the transesterification, the catalyst from the first step can optionally be blocked by addition of phosphorous acid or phosphoric acid, or, as in the case of tin (IV), reduced with a phosphite such as triphenyl phosphite or tris (nonylphenyl) phosphite or those listed in paragraph [0034] of application US 2011282020 a 1.

The second stage of condensation of the oligomers may optionally be carried out with addition of a catalyst. The catalyst is advantageously selected from tin derivatives, preferably tin, titanium, zirconium, germanium, antimony, bismuth, hafnium, magnesium, cerium, zinc, cobalt, iron, manganese, calcium, strontium, sodium, potassium, aluminium or lithium derivatives, or mixtures of these catalysts. Examples of such compounds may be, for example, those given in patent EP 1882712B 1 in paragraphs [0090] to [0094 ].

Preferably, the catalyst is a derivative of tin, titanium, germanium, aluminum or antimony.

By way of example of amounts by weight, from 10 to 500ppm of the metal contained in the catalytic system can be used during the oligomer condensation stage, with respect to the amount of monomer introduced.

Most preferably, the catalytic system is used during the first and second stages of the polymerization. The system advantageously consists of a tin-based catalyst or a mixture of tin-, titanium-, germanium-and aluminium-based catalysts.

for example, the metal contained in the catalytic system may be used in an amount of 10 to 500ppm by weight with respect to the amount of monomer introduced.

According to this preparation method, antioxidants are advantageously used during the polymerization step of the monomers. These antioxidants make it possible to reduce the coloration of the polyester obtained. The antioxidant may be a primary antioxidant and/or a secondary antioxidant. The primary antioxidant may be a sterically hindered phenol, such as a compound0 3、0 10、0 16、210、276、10、76、3114、1010 or1076 or phosphonates such as195. the secondary antioxidant may be a trivalent phosphorus compound, such as626、S-9228、P-EPQ or Irgafos 168.

At least one compound capable of limiting the undesired etherification reaction, such as sodium acetate, tetramethylammonium hydroxide or tetraethylammonium hydroxide, may also be introduced into the reactor as a polymerization additive.

Finally, the process comprises a step of recovering the polyester at the end of the polymerization step. The thermoplastic polyester thus recovered can then be used as a thermoplastic matrix in the process described according to the invention.

Semi-crystalline polyesters particularly suitable for obtaining thermoplastic fibers can be prepared by a synthetic process as previously described, but as a variant, wherein the molar ratio of (a)/[ (a) + (B) ] is at least 0.05 and at most 0.30, said process also comprising a step of increasing the molar mass.

The step of increasing the molar mass is carried out by post-polymerization and may comprise a step of Solid State Polycondensation (SSP) of the semi-crystalline thermoplastic polyester or a step of reactive extrusion of the semi-crystalline thermoplastic polyester in the presence of at least one chain extender.

Thus, according to a first variant, the post-polymerization step is carried out by SSP.

SSP is generally carried out at temperatures between the glass transition temperature and the melting point of the polymer. Therefore, in order to perform SSP, the polymer must be semicrystalline. Preferably, the latter has a heat of fusion of greater than 10J/g, preferably greater than 20J/g, the measurement of which comprises subjecting a sample of such polymer having a lower solution reduced viscosity to a heat treatment at 170 ℃ for 16 hours, then evaluating the heat of fusion by DSC by heating the sample at 10K/min.

Advantageously, the SSP step is carried out at a temperature ranging from 190 ℃ to 280 ℃, preferably ranging from 200 ℃ to 250 ℃, which step must be carried out at a temperature lower than the melting point of the semi-crystalline thermoplastic polyester.

The SSP step can be carried out under an inert atmosphere, for example under nitrogen or under argon or under vacuum.

According to a second variant, the post-polymerization step is carried out by reactive extrusion of the semi-crystalline thermoplastic polyester in the presence of at least one chain extender.

The chain extender is a compound comprising two functional groups capable of reacting with the alcohol, carboxylic acid and/or carboxylate functional groups of the semi-crystalline thermoplastic polyester in reactive extrusion. The chain extender may for example be selected from compounds comprising two isocyanate, isocyanurate, lactam, lactone, carbonate, epoxy, oxazoline and imide functions, which may be identical or different. Chain extension of the thermoplastic polyester can be carried out in all reactors capable of mixing, with stirring, a very viscous medium which is sufficiently dispersed to ensure a good interface between the molten material and the gaseous head space of the reactor. A particularly suitable reactor for this treatment step is extrusion.

The reactive extrusion can be carried out in any type of extruder, in particular a single-screw extruder, a co-rotating twin-screw extruder or a counter-rotating twin-screw extruder. However, it is preferred to use a co-rotating extruder for such reactive extrusion.

The reactive extrusion step may be carried out by:

Introducing a polymer into an extruder so as to melt the polymer;

Then introducing the chain extender into the molten polymer;

Then reacting the polymer with the chain extender in an extruder;

Then recovering the semi-crystalline thermoplastic polyester obtained in the extrusion step.

During extrusion, the temperature inside the extruder is adjusted to exceed the melting point of the polymer. The temperature inside the extruder may range from 150 ℃ to 320 ℃.

The semi-crystalline thermoplastic polyester obtained after the step of increasing the molar mass is recovered and can then be used to obtain the thermoplastic fiber according to the invention.

a second subject of the invention relates to a process for producing a thermoplastic composite, comprising the steps of:

a) A thermoplastic polymer matrix as described previously is provided,

b) Providing a thermoplastic polymer fiber as described previously,

c) Preparing a thermoplastic composite from the matrix and the fibers.

According to one embodiment, the polymer matrix is provided in such a way that the thermoplastic composite comprises from 30 to 80% by weight, preferentially from 40 to 70% by weight of semi-crystalline thermoplastic polyester fibers as previously described.

Step c) of the method according to the invention comprises preparing a thermoplastic composite from the matrix and the fibres described previously.

This preparation step may be carried out by mixing or incorporating the fibers into a polyester matrix, followed by a shaping step. For the purposes of the present invention, the terms "impregnation" and "wetting" are synonymous. The incorporation may include impregnating the semicrystalline thermoplastic polyester fibers with an amorphous thermoplastic polyester matrix. Incorporation according to the process of the invention can be carried out by techniques known to the person skilled in the art, for example by melt impregnation. After impregnation, a shaping step may be carried out, which shaping may also be carried out according to the techniques of the person skilled in the art, for example by compression/punching, by pultrusion, by low pressure under vacuum or by filament winding.

According to one embodiment, the incorporation is carried out by melt impregnation and the shaping is carried out by hot compaction. According to this embodiment, the semicrystalline thermoplastic polyester fibers may be in the form of a plain weave pattern that may be cut and placed between two sheets of amorphous matrix. The assembly is then placed in a press, heated above the Tg of the matrix, and pressed to obtain a board in which the fibres are impregnated with the matrix.

The assembly is then reheated and placed in a cold mold. After pressing and cooling, the assembly obtained constitutes a thermoplastic composite, the semicrystalline thermoplastic polyester fibers being completely incorporated in the amorphous thermoplastic polyester matrix, and said composite being particularly strong.

The method according to the invention is therefore particularly advantageous, since it enables composite materials to be obtained that are completely thermoplastic (both matrix and fibrous reinforcement), thus resulting in an ease of recycling that has never been achieved to date.

the thermoplastic composite material according to the invention is therefore most particularly suitable for the manufacture of plastic articles or objects and can therefore be used in many active fields, such as automotive, aircraft, naval, construction or sports. Indeed, they may be used, for example, for the manufacture of automotive parts, such as door inner parts, boat hulls, or for the manufacture of building materials.

the thermoplastic composite material according to the invention will also be most particularly suitable for the manufacture of parts in the field where a reduction in the overall weight of the structure is sought.

The invention will be more clearly understood by means of the following examples, which are intended to be purely illustrative and do not in any way limit the scope of protection.

Examples of the invention

the properties of these polymers were investigated via the following techniques:

reduced viscosity of solution

After dissolution of the polymer at 130 ℃ with stirring, the solution reduced viscosity was evaluated at 25 ℃ in an equal mass mixture of phenol and o-dichlorobenzene using an Ubbelohde capillary viscometer, the concentration of the polymer introduced being 5 g/l.

DSC

The thermal properties of the polyesters were measured by Differential Scanning Calorimetry (DSC): the sample was first heated from 10 ℃ to 320 ℃ (10 ℃ C. min in an open crucible under nitrogen atmosphere^-1) Cooling to 10℃(10℃.min^-1) And then heated again to 320 c under the same conditions as the first step. The glass transition temperature was taken at the midpoint of the second heating. Any melting point (peak onset) was determined on the endothermic peak at the first heating.

Similarly, the melting enthalpy (area under the curve) is determined at the first heating.

For the illustrative examples presented below, the following reagents were used:

1, 4-cyclohexanedimethanol (99% purity, mixture of cis and trans isomers)

Isosorbide (purity)>99.5%) from Roquette freres, FranceP

Terephthalic acid (99 +% purity) from Across corporation (Acros)

From BASF AG1010

Dibutyl tin oxide (98% purity) from Sigma-Aldrich

preparation of thermoplastic composites

A. Preparation of thermoplastic fibers

1)Polymerisation

The thermoplastic polyester P1 is a semi-crystalline thermoplastic polyester prepared according to the procedure wherein the molar ratio of the sum of 1,4:3, 6-dianhydrohexitol units (a)/diol monomers, i.e. (a) must be added to cycloaliphatic diol units (B) other than these 1,4:3, 6-dianhydrohexitol units (a), i.e. (a)/[ (a) + (B) ], is at least 0.05 and at most 0.30.

Thus 1432g (9.9mol) of 1, 4-cyclohexanedimethanol, 484g (3.3mol) of isosorbide, 2000g (12.0mol) of terephthalic acid, 1.65g of Irganox 1010 (antioxidant) and 1.39g of dibutyltin oxide (catalyst) are added to a 7.5l reactor. Once the reaction medium temperature was at 60 ℃,4 vacuum-nitrogen cycles were performed.

The reaction mixture was then heated to 240 ℃ (4 ℃/min) under a pressure of 6.6 bar and with constant stirring (150rpm) until a degree of esterification of 40% was obtained. The degree of esterification was estimated from the mass of distillate collected. Once this level was reached, the temperature of the reaction mixture was brought to 250 ℃ until a degree of esterification of 55% was obtained. Once this level was reached, the reactor pressure was reduced to atmospheric pressure and the temperature was brought to 260 ℃ until an 80% degree of esterification was obtained. The pressure was then reduced to 0.7 mbar and the temperature reached 280 ℃ according to a logarithmic gradient over the course of 120 minutes.

These vacuum and temperature conditions were maintained until a torque increase of 12.1Nm relative to the initial torque was obtained.

finally, polymer rods were cast through the bottom valve of the reactor, cooled in a thermally conditioned water bath at 15 ℃ and chopped in the form of about 15mg of granules.

The resin thus obtained had a density of 80.1ml/g^-1Reduced viscosity of the solution of (a).

Process for preparing polyesters¹h NMR analysis showed that the final polyester contained 17.0 mol% isosorbide with respect to the diol.

With regard to the thermal properties, the polymer had a glass transition temperature of 96 ℃ and a melting point of 253 ℃ with a melting enthalpy of 23.2J/g.

10kg of these pellets were subjected to a solid-state post-condensation step at 210 ℃ under a nitrogen stream (1500l/h) for 20h in order to increase the molar mass. The resin after solid state condensation had a mass of 103.4ml^-1Reduced viscosity of the solution of (a).

The polyester granules thus obtained can then be shaped so as to obtain thermoplastic fibres.

2)Shaping by

The granules of polyester P1 obtained in polymerization step 1) were dried at 140 ℃ under nitrogen so as to reach a residual moisture content of the granules of less than 300ppm and in particular 105 ppm.

These pellets were then introduced into an extruder with 5 heating zones: the particle introduction zone is 300 ℃, 295 ℃ in zone 2, 290 ℃ in zone 3, 285 ℃ in zone 4, 280 ℃ in zone 5, and 278 ℃ in the tube, in the material driven pump, and in the filter for removing the gel and the spinning head (in the direction of circulation of the stream of molten material).

The head used in this example enables the formation of monofilaments and multifilaments. According to this example, the die comprises 10 orifices with a capillary diameter of 0.5mm and a driving speed of 2000m/min, which orifices are adjusted to a flow rate to have a material flow rate of 1.5g/min per orifice.

At the outlet of the spinning head, the various filaments combined at the point of convergence are cooled by a stream of air at 25 ℃ and then wound by means of a winding machine.

Subsequently, these reels are mounted on a loom so as to obtain a plain type weave pattern. A plain weave type of woven thermoplastic fiber is thus obtained.

B. Preparation of thermoplastic matrix

1.Polymerisation

To obtain a thermoplastic matrix, a second thermoplastic polyester P2 was prepared according to the same procedure as polyester P1. This second polyester P2 is an amorphous thermoplastic polyester. The amounts of the compounds used are detailed in table 1 below:

TABLE 1

The resin thus obtained using polyester P2 had a density of 54.9ml/g^-1Reduced viscosity of the solution of (a).

Process for preparing polyesters¹h NMR analysis showed that the final polyester contained 44 mol% isosorbide with respect to the diol. With respect to thermal properties, the polymer has a glass transition temperature of 125 ℃.

After analysis, polyester P2 was not characterized by the presence of X-ray diffraction lines even after heat treatment at 170 ℃ for 16h and by the presence of an endothermic melting peak in Differential Scanning Calorimetry (DSC) analysis. Thus, polyester P2 was amorphous.

2.Shaping by

The P2 pellets were dried under vacuum at 110 ℃ for 4 h. The moisture content before casting extrusion was 287 ppm. Cast extrusion was performed using a Collin extruder equipped with a flat die.

These pellets were kept in a dry atmosphere and conveyed directly into the hopper of the extruder. Extrusion of polymer P2 on woven thermoplastic fibers was performed using the following temperatures: 230 ℃/225 ℃/225 ℃/220 ℃ (4 heating zones, die- > feed). The screw speed was 80rpm and the temperature of the rolls of the calendering machine was 50 ℃.

The obtained sheet had a thickness of 500 μm.

C. forming thermoplastic composites

The preparation is carried out by pressing, which is carried out on a Carver press.

A square of thermoplastic fibers woven according to a plain weave pattern is secured between two extruded sheets which are themselves arranged between the plates of a press (part type: plates).

The temperature of the plate was set at 160 ℃ and pressure was applied on the material in order to obtain good impregnation of the thermoplastic fibres with the thermoplastic matrix. The weight of the woven thermoplastic fibers was 50% by weight of the total weight of the plain weave thermoplastic fibers and the molten material. After 2 minutes of contact, the temperature of the plate was lowered to 50 ℃.

Thus, a thermoplastic composite material in the form of a sheet is obtained, in which the impregnation is fully achieved despite the thermoplastic nature of the fibres and the matrix. This is explained in particular by the semi-crystalline appearance of the thermoplastic fibers and their higher melting point compared to the melting point of the amorphous thermoplastic matrix. The thus obtained sheet can also be reheated and thermoformed in the form of, for example, a tub.

Strips were cut from the thus obtained plate, and mechanical properties were measured. An improvement in the mechanical properties compared to the matrix alone is observed, in particular with regard to the tensile properties.

Recycled thermoplastic composites

The composite part obtained was ground, dried under vacuum at 110 ℃ for 4h (moisture content 320ppm), mixed with 100ppm of dibutyltin oxide, then extruded at a uniform temperature of 280 ℃, then cooled in a cold water bath and granulated.

Differential scanning calorimetry analysis of the particles thus obtained showed that the melting peak was reduced to the occurrence of a glass transition at 253 ℃ and about 110 ℃. These observations thus demonstrate that transesterification reactions occur in the material during heating to a temperature greater than the melting point of the thermoplastic fibers. Thus, during recycling at said temperatures, a material is obtained which comprises compatible phases or even completely homogeneous.

The thermoplastic composite material according to the invention is therefore particularly advantageous in that it is no longer necessary to separate the fibers from the matrix for its recycling. The step of heating to a temperature greater than the temperature of the thermoplastic fibers readily enables thermoplastic materials to be obtained that can then be reused in a variety of applications.

Claims

1. A thermoplastic composite, comprising:

2. Thermoplastic composite according to claim 1, characterized in that the cycloaliphatic diol (B) is a diol selected from 1, 4-cyclohexanedimethanol, 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol or a mixture of these diols, very preferably 1, 4-cyclohexanedimethanol.

3. Thermoplastic composite according to one of claims 1 and 2, characterized in that the amorphous and semi-crystalline thermoplastic polyesters do not contain any aliphatic acyclic diol units, or contain aliphatic acyclic diol units in a molar amount of less than 1% relative to all monomer units of the polyester, preferably the polyester does not contain any aliphatic acyclic diol units.

4. Thermoplastic composite according to one of claims 1 to 3, characterized in that the molar ratio of (3, 6-dianhydrohexitol units (A) + cycloaliphatic diol units (B))/(terephthalic acid units (C)) other than the 1,4:3, 6-dianhydrohexitol units (A) is from 1.05 to 1.5.

5. Thermoplastic composite according to one of claims 1 to 4, characterized in that the 1,4:3, 6-dianhydrohexitol (A) is isosorbide.

6. Thermoplastic composite according to one of claims 1 to 5, characterized in that it comprises 20 to 70% by weight, preferentially 30 to 60% by weight, of amorphous thermoplastic polyester matrix.

7. Thermoplastic composite according to one of claims 1 to 6, characterized in that it comprises 30 to 80% by weight, preferentially 40 to 70% by weight of semicrystalline thermoplastic polyester fibers.

8. A method for producing a thermoplastic composite, the method comprising the steps of:

-providing a polymer matrix, said polymer being an amorphous thermoplastic polyester comprising at least one 1,4:3, 6-dianhydrohexitol unit (A), at least one cycloaliphatic diol unit (B) other than the 1,4:3, 6-dianhydrohexitol units (A), at least one terephthalic acid unit (C), wherein the ratio of (A)/[ (A) + (B) ] is at least 0.32 and at most 0.75, said polyester being free of any aliphatic acyclic diol unit or comprising an aliphatic acyclic diol unit in a molar amount of less than 5% relative to all monomer units of the polyester, and the solution reduced viscosity of said polyester (25 ℃; phenol (50% m): o-dichlorobenzene (50% m); 5g/l of polyester) being greater than 50ml/g,

-providing a polymer fiber, said polymer being a semi-crystalline thermoplastic polyester comprising at least one 1,4:3, 6-dianhydrohexitol unit (a), at least one cycloaliphatic diol unit (B) other than the 1,4:3, 6-dianhydrohexitol units (a), at least one terephthalic acid unit (C), wherein the ratio of (a)/[ (a) + (B) ] is at least 0.05 and at most 0.30, said polyester being free of any aliphatic acyclic diol unit or comprising an aliphatic acyclic diol unit in a molar amount of less than 5% relative to all monomer units of the polyester, and the solution reduced viscosity of said polyester (25 ℃; phenol (50% m): o-dichlorobenzene (50% m); 5g/l of polyester) is greater than 50 ml/g;

-preparing a thermoplastic composite from the matrix and the fibres.

9. The process according to claim 8, wherein the cycloaliphatic diol (B) is a diol selected from 1, 4-cyclohexanedimethanol, 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol or a mixture of such diols, very preferably 1, 4-cyclohexanedimethanol.

10. The production process according to one of claims 8 and 9, characterized in that the thermoplastic polyester does not contain any aliphatic acyclic diol units, or contains aliphatic acyclic diol units in a molar amount of less than 1% relative to all monomer units of the polyester, and preferably the polyester does not contain any aliphatic acyclic diol units.

11. The process according to any one of claims 8 to 10, wherein the 1,4:3, 6-dianhydrohexitol (A) is isosorbide.

12. The production method as claimed in one of claims 8 to 11, characterized in that the preparation step is carried out by impregnation with a melt followed by a shaping step by compression/punching, by pultrusion, by low pressure under vacuum or by filament winding.